Intragastric movement assessment by measuring magnetic field decay of magnetised tracer particles in a solid meal

The aim of the study is to evaluate and further develop a non-invasive meth od for the measurement of intragastric movements. Ferrimagnetic particles ( gamma-Fe2O3) are ingested within a standard test meal (pancakes), and given a permanent magnetisation by an applied homogeneous magnetic field. Magnet ic measurements are performed outside the stomach, using fluxgate magnetome ters anterior and posterior, in seven periods of 12 minutes each. Any movem ents caused by grinding and mixing in the ingesta would result in a misalig nment of the magnetic moments, and hence in a decay of the external magneti c field. Twelve healthy male volunteers, aged 26.7 +/- 2.7 years (mean +/- SD), are studied. After an initial phase of low and almost linear flux dens ity decay (32 +/- 19%, from minute 10 to minute 22 postprandially), the mea n rotation and decay gradually increases (67 +/- 21%, from minute 100 to 11 2), and the decay becomes bi-exponential. It is hypothesised that the biexp onential nature of the decay corresponds to the relative fractions, solid a nd semifluid, of gastric content. The decay curves often show superimposed 3 cycles min(-1) variations, which correlate well with the basic electrical rhythm of the stomach measured by electrogastrography (EGG). It is conclud ed that these variations are induced by gastric contractions.